Two aspects of data storage devices are under constant pressure for enhancement. One is the continuing effort to increase storage density and the other is the continuing development work directed to the reduction of response time by higher speed components or improved techniques.
Storage density is increased by increasing bit densities and by narrower, more closely spaced data tracks. These changes result in a reduction of the size of the bit domains which requires that the reading and writing capabilities be upgraded to higher levels of performance to maintain the same standard of reliability previously attained.
Among the characteristics that are designed to optimize drive performance are the write current supplied to the transducer during the write operating mode and during the reading mode, the delta-V, which is the voltage change per unit time threshold which is used to discriminate between data and noise signals on the channel. It has been common practice to set both of these values to obtain optimum performance. However, with both of these parameters, the value that obtain best performance varies from transducer to transducer and also with the radial position of transducer location which is a function of the speed of the head relative to the media surface. Another problem that arises is the phenomena that components that test as being within the product specification can fail to function properly in combination with other components, while components that appear to fail with respect to specification standards, may function properly in combination with other components.